The present claimed invention relates to the field of optically scanning a surface of a document or work of art. More specifically, the present claimed invention relates to the use of a freehand optical scanner of images from documents or other printed or written media for the purpose of inspecting and authenticating documents or works of art.
Digital imaging has come of age. Equipment that was once regarded as cutting edge technology is now commonplace on the desktop. The powerful computers required to manipulate digital images are now considered entry level, so it is not surprising to learn that optical scanners, the devices used to get optical images into a computer as digital images, form the basis of one of the fastest growing markets today. Hereafter, the terms xe2x80x9coptical scanningxe2x80x9d and xe2x80x9coptical scannerxe2x80x9d will be referred to more simply as xe2x80x9cscanningxe2x80x9d and xe2x80x9cscannerxe2x80x9d respectively.
On the simplest level, a scanner is a device that converts light into 0s and 1s (a computer-readable format). More simply, scanners convert analog data into digital data. All scanners work on the principle of sensing light reflected, transmitted, or emitted from a surface. Scanners usually contain a light source and an image sensor. If scanning speed is not required, ambient illumination can sometimes be used instead of having a built-in light source.
To direct light from the source to the sensor that reads light values, scanners may use prisms, lenses, and other optical components. The amount of light reflected, transmitted, or emitted by the object being scanned is picked up by the sensor and converted to voltages by a photo sensor array.
Photo sensor array technology is responsible for having made scanning a desktop application and has been in use for a number of years in devices such as fax machines and digital cameras. A photo sensor array is a solid state electronic device that converts light into electric signals. A desktop scanner sensor typically has thousands of photosensitive elements arranged in a long thin line. Each photosensitive element acts as a photometer, converting measured light into an electric signal, which can then be sampled and changed to discrete digital values by an analog-to-digital converter (ADC).
An advancement in scanner technology is optical character recognition (OCR). OCR is a method for recognition of typeset, typed, and, in some cases, hand-printed letters, numbers, and symbols using optical sensing technology as mentioned above. The light reflected by a typed document, for example, is recorded as patterns of light and dark areas by a scanner. A computer program analyzes the patterns and identifies the characters they represent, with some tolerance for less than perfect and uniform text. OCR is also used to produce text files from computer files that contain images of alphanumeric characters, such as those produced by fax transmissions.
Unfortunately, while OCR offers many benefits, it also has some limitations. OCR has difficulties when deciphering hand written characters. Handwriting is hard to deal with because some handwriting is so fancy or messy that it hardly constitutes writing. Even more so, OCR has very limited capabilities for recognizing signatures.
In one prior art system (U.S. Pat. No. 5,227,642), dark-field optics are used for optically reading surface textures. This invention is mostly used for reading embossments and is not useful with papa media because the paper scatters most of the incident light. In addition, (U.S. Pat. No. 5,432,868) claims a scanning device for the recognition of signatures. In this invention, a classical scanning device is used to sense the time intervals between detected stroke lines. The stroke information is processed using frizzy logic.
In other prior art systems, (U.S. Pat. No. 4,128,829) xe2x80x9cSignature Verification Method and Apparatus Utilizing Both Acceleration and Pressure Characteristicsxe2x80x9d and (U.S. Pat. No. 3,983,535) xe2x80x9cSignature Verification Method and Apparatusxe2x80x9d Image correlation is applied to the ink, but microscopic detail of the media surface is not considered.
Furthermore, (U.S. Pat. No. 5,578,813) xe2x80x9cFreehand Image Scanning Device Which Compensates for Non-linear Movementxe2x80x9d describes a scanner with navigation cameras that see the microscopic detail of a media surface. Additionally, (U.S. Pat. No. 5,686,720) xe2x80x9cMethod and Device for Achieving High Contrast Surface Illuminationxe2x80x9d describes the use of grazing illumination for improving the contrast of images of microscopic detail of a media surface.
Identification through one""s signature occurs during many everyday transactions. Any process or transaction that requires an individual""s signature, is a prime contender for signature identification. The major technological hurdle for signature identification involves the method of trying to differentiate between the parts of the signature that are habitual and those that vary with each signing.
Even more difficult is authenticating original documents or items that have signatures on them. With the advancements in optical scanning and printing, the importance of distinguishing between forgeries and originals has heightened. The quality of reproductions has risen to a level where it is nearly impossible to distinguish or identify originals with the human eye. Even with the help of OCR technology, it remains nearly impossible to quickly identify a document as an original.
Thus there has arisen a need for a device that can quickly and reliably identify signatures and documents as originals. Additionally, such a device could be used to identify other surface features, such as artwork, and authenticate their originality.
Accordingly, the present invention provides a portable device capable of recognizing and identifying signatures and surface features of media. More specifically, in one embodiment, this invention pertains to the use of an image scanner for inspecting signatures or other handwriting on a material surface for the purpose of authenticating the signature or originality of a document or article.
More specifically, the present invention includes a scanning device for acquiring images from a surface containing signatures. The scanning device includes a memory for retaining template image characteristics of known signatures, a processor for comparing image characteristics of known signatures to those of the scanned image, logic used to determine if the characteristics of the scanned image are similar to the image characteristics of the known signature, and an output device for giving the user an output of the probability that the scanned signature closely matches the template image stored on the device.